This invention relates to a washing machine for scrubbing and cleaning objects with a washing fluid and to a method of using the machine. The method and apparatus are useful for cleaning worn machine parts prior to reconditioning the parts.
In many types of mechanical devices and machines, parts of the devices are exposed to dirt, grease, and other solid and liquid contaminants that impede the performance of the device. In other cases, parts of the devices deteriorate through normal wear, and while they can be removed from the machine, reconditioned and reinstalled, the parts may be so contaminated with dirt and grease that reconditioning is impractical. It is necessary to thoroughly clean the dirty or worn parts when these conditions are encountered.
Washing the parts with water is a desirable cleaning method, but this method is not acceptable when the contaminants are not readily soluble in water. The use of organic solvents can greatly aid cleaning, but the cost is usually prohibitive. Furthermore, solvent vapors must generally be incinerated or recovered in order to meet State and Federal standards for the discharge of volatile organic solvents. In addition, the spent solvent must either be recovered for reuse or discarded in such a way as to comply with current waste disposal laws. In any event, the use of volatile organic solvents is costly and poses environmental risks.
The need to recondition vehicle parts, such as automotive and truck brake shoes, presents a significant challenge. A brake shoe is a shaped metal part having a brake pad, such as an asbestos pad, riveted to the metal part. The shaped metal part forming the major portion of the brake shoe is costly to manufacture. In addition, brake shoes come in a variety of shapes and sizes and it is impractical to maintain an inventory of all of the different types. For these reasons, it is frequently advantageous to recondition the brake shoe by removing and replacing the brake pad. Commercial shops exist throughout the nation to perform this important service for truckers. Time is of the essence, since a vehicle is removed from service while the brake shoes are being reconditioned.
Worn brake shoes are usually covered with a heavy encrustation of dirt and other solid matter. In addition, the worn shoes are frequently contaminated with grease, oil, and sludge. These contaminants cover the rivets holding the brake pad on the brake shoe and also prevent easy removal of the pad by acting as a bonding medium along the edges of the brake pad and the surface of the brake shoe. Thus, before the brake pad can be removed from the worn brake shoe, the dirt, grease, and other contaminants must be removed. Soaking the worn brake shoe in water is not sufficient, since the contaminants are not readily soluble in water. Manual scraping of the parts is not practical for economic reasons; not only is manual labor costly, but manual cleaning is slow, which can extend the time required to return the vehicle to service.
Thus, there exists a need in the art for an apparatus and a method for cleaning mechanical parts covered with solid dirt, grease, oil and other contaminants. The method and apparatus should be suitable for removing water soluble as well as water insoluble contaminants from the parts. The apparatus and method should also be suitable for removing heavy encrustations of solid matter, which are not practically removed by manual scraping. Since the parts will be reconditioned and reused, it is important that the apparatus and method make it possible to non-destructively clean the parts. The apparatus and method should be relatively simple, be of low cost, and require relatively low maintenance during operation. It would be highly advantageous if the cleaning time was relatively short so that the vehicle or machine from which the parts were removed could be quickly restored to service. The method and apparatus should require relatively small amounts of cleaning fluid and should be capable of cleaning parts with water as the principal cleaning fluid. If organic solvents are used, the amounts required should be relatively small. In addition, the cleaning fluid should be reusable.